Saving Energy: Best-Practices & System View

During the recent State of the Union Address, President Obama issued a new goal for America: “Let’s cut in half the energy wasted by our homes and businesses over the next 20 years.”

Looking at the options for saving electrical energy in US factories, industry experts say it’s important not only to look at a number of different technologies but also to adopt a new mindset. Premium efficiency electric motors, adjustable speed drives, and both permanent magnet and synchronous reluctance motors are all areas where energy-efficient motor technology is moving ahead. But the real focus should be to emphasize not only best-practices but also a “system versus component view” in targeting how to reduce energy consumption.

“When we look at the whole problem, we really want to look at the system,” John Malinowski, product marketing manager for ABB Baldor, told Design News. “We should be beyond component replacement at this point because it doesn’t do any good to put a 96 percent efficient motor on a 50 percent efficient pump, compressor, fan, or whatever.”

Motor system energy consumption often puts the emphasis on usage by pumps, fans, and compressors, but there are many additional energy saving opportunities that require more of a system view. (Source: US Department of Energy)

Malinowski said the key is to look all aspects of industrial systems, and even factors as simple as mechanical power transmission. An older double reduction worm gearbox, for example, might be 50 percent to 60 percent efficient. If the gearbox with a 10 HP motor is providing a certain amount of torque to run a conveyor, switching to a helical or helical bevel gearbox that is 95 percent efficient means the 10 HP motor can be replaced with a 5 HP model and eliminate large inefficiencies due to mechanical losses.

Looking at the system is critical, even though we can look at all of the pump, fan, and variable torque applications that follow the Affinity Law where horsepower changes by the cube of the speed. That low-hanging fruit has been a primary target for a long time, but Malinowski said we still have companies that don’t understand those opportunities.

But even on a constant torque load conveyor if we use system efficiency at the guide, using an adjustable speed drive and the flow of product to work in harmony with other production processes can produce results. Engineers may not be able to track these results on the utility meter, but benchmarking kilowatt-hours per widget produced shows the savings. Servos use more energy than a regular motor because of the inrush current to move quickly, but products are moving between workstations more quickly, and more work is produced per hour.

“We need to develop a different mindset,” Malinowski told us. “That is the trend we see, so that when we look at systems we see anything inside the electrical meter. We have the power distribution transformer, the smart soft starter or drive, motors, and mechanical transmission. Using best-practices, we can raise efficiency and reduce power.”

Part of the problem given our current economy is the reluctance of companies to make “first cost” investments that take time to pay off versus life costs. Motor suppliers point to lifecycle costs of a motor of which only 2 percent is the initial purchase price, versus more than 97 percent for the electricity to operate the motor over its lifetime. The only way to change the electrical contribution is to use the motor less, use a smaller model, or use a more efficient solution.

Malinowski says that especially small and midsized plants still see the electrical bill as something they can’t manage, and view it as a fixed operating cost. While the mindset is changing, smaller companies have fewer resources to emphasize energy management and reduction.

The good news is that most utilities have pro-active programs to emphasize efficiency gains, along with EnergyStar and the US Department of Energy. The key is overcoming inertia especially in an economy where companies are emphasizing ways to create additional business.

Using best-practices, the DOE says industrial plants can save 11 percent to 18 percent on a plant’s electric bill (two-thirds of which is electric motor-driven systems, and in some industries it climbs as high as 90 percent). What company wouldn’t want to reduce that bill by 18 percent or more? The key is mobilizing resources and reaching out to local utilities, plus investigating rebates and incentives that reduce the cost of energy saving upgrades. A good place to start is the US Department of Energy website.

apresher - I noticed that starting to pick up about 5 years ago. Prior to that, customers who wanted energy monitoring meters were few and far between. All of a sudden, it seemed like everybody wanted them.

Until recently, energy was viewed as a fixed expense to there was not as much focus on how to reduce utility bills. Now with some of the Ethernet-based energy protocols, one long-term goal is to measure the energy used to create a product so it can be added to the bill of materials. Would be a giant step forward.

Interesting point about efficiency versus wastefulness, TJ. It's amazing to think that many factories are indeed so wasteful, especially when it directly affects their own bottom lines. Unfortunately, I believe you're right when you say that the factories need to do their part and turn off systems when not in use.

a.saji, I agree with you that putting machinery into low power mode during idle times seems like a no-brainer. Newer network energy control protocols (PROFIenergy, SERCOS Energy and CIP Energy) are just coming onstream and offer a path to achieving these benefits.

Ann, There has been an emphasis on replacing drives on fans and pumps with higher efficiency solutions. And that will continue. In U.S. factories, motor-driven systems account for over 60 percent of the total energy consumed, and roughly 25 percent of total U.S. overall energy use. Because these numbers are so big, the opportunities/challenges are large and diverse.

"Some of the new developments that would automatically put machinery into Sleep mode when not in use"

Apresher: I guess this is done to save whatever the energy left when the machine is in idle mode. To be honest I feel it's a good method. We should save in whatever the method possible for us so the future generation can benefit out of it.

It's interesting to see system-wide energy saving strategies entering into the design of industrial systems, after a (relatively) long history in electronics design. I'd guess many of the system-wide issues and strategies would be similar, such as a sleep mode. TJ mentions factory systems, such as HVAC systems: haven't these already been energy-reduced, as part of/in concert with the effort to reduce energy in the data center over the last decade or so?

TJ, Some of the new developments that would automatically put machinery into Sleep mode when not in use (production pauses) should begin to provide some of the practical solutions you're talking about. But not all of the solutions need to be high tech as you point out.

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